Olfactory Marker Protein in the Human Carotid Body

Background: Transduction mechanisms of the hypoxic chemoreflex elicited by carotid body (CB) chemoreceptor cells remain unclear. Recent studies direct attention to the plausible link between CB and olfactory chemoreceptor functions.Methods: Here we used immunohistochemistry to investigate the distribution and localization of olfactory marker protein (OMP) in human CB. Carotid bodies were collected post-mortem from hospital patients aged 27-76 years who died from reasons unre-lated to chronic pulmonary or cardiovascular disorders. We used specific antibodies to selectively identify CB cells and OMP in tissue sections. The binding of antibodies to target antigens was visualized with the Ultra Vision detection system.Results: We show that OMP is abundantly present in the cytoplasm of CB chemoreceptor cells. The presence of OMP in these cells indicates that the olfactory system may participate in shaping the chemosensory CB function.Conclusions: The findings support the notion that the transduction mechanisms of chemoreceptive systems contain a degree of homology, irrespective of the anatomical localization and the functional role these systems fulfill. The ectopic presence of OMP in CB broadens the current understanding of the mechanisms underlying chemosensory responses.